The present invention relates to a liquidtight tank or reservoir made of prestressed reinforced concrete, particularly for purification plants.
The tank or reservoir according to the invention is particularly convenient also for the storage of incoherent materials, for instance cereals in general.
The known technique of construction of tanks or reservoirs both of normal reinforced concrete and prestressed reinforced concrete is so wide that it is not deemed suitable to discuss it herein; it is sufficient to mention some of the constructional and manufacturing methods which are used presently, pointing out some disadvantages deriving therefrom, the prevention of such disadvantages being, among other things, the object of the present invention.
According to a first technique of construction, the tanks or reservoirs are pre-fabricated as an integral body up to dimensions which are compatible with the transport problem. Over certain dimensions, owing to a practical impossibility of transport, they are constructed directly on the spot according to well known methods of construction.
A common feature of these techniques of construction is their hand-made character, which nowadays constitutes a significant disadvantage, mainly because of the high costs of labor deriving therefrom.
Moreover, the prestress of the concrete is, from the technical point of view, a complex operation, so that if tanks or reservoirs are to be constructed of normal reinforced concrete, a considerable quantity of material is required which represents a further cost in addition to the cost of the labor which is high in itself.
Other techniques of construction exist which allow the manufacture of the tanks or reservoirs by assembling on the spot elements of normal or prestressed reinforced concrete, having each a radius of curvature equal to the bending radius of the cylindrical tank. It can easily be appreciated that while an element having a fixed radius of curvature generally gives rise to a cylindrical tank having the same bending radius, a plane element can give rise to polygonal tanks having a different number of sides according to the inclination between adjacent elements.
In other words, if tanks of different capacities are to be constructed it is necessary to vary either the height of said elements or, anyway, the radius of curvature, i.e., each element gives rise to a tank of determined capacity, and the provision of a tank having a different capacity requires the use of an element having other characteristics. To understand clearly the limits which practically are set to the use of such techniques it is sufficient to consider the enormous quantity of forms which are necessary for the provision of the various types of elements required for the manufacture of all the various types of containers demanded by the market.